1. Field of the Invention
Apparatuses consistent with the present invention relate to a heat-assisted magnetic recording head and, more particularly, to a heat-assisted magnetic recording head for heating a magnetic recording medium locally by irradiating a light beam, and a recording apparatus including the same.
2. Description of the Related Art
Extensive research has been conducted into methods of enhancing recording density in the field of magnetic information recording. In order to enhance recording density, the size of bits of a magnetic recording medium must be reduced, and transition noise must be reduced by making the size of grains constituting the bits smaller.
Meanwhile, in order to retain information recorded on a magnetic recording medium stably, the coercive force of the magnetic recording medium must be sufficiently large. However, in the case of a magnetic recording medium having a large coercive force, information recording may be impossible due to the limitation of the strength of a magnetic field generated by a magnetic recording head. In order to overcome this problem, a heat-assisted magnetic recording head has been devised. A heat-assisted magnetic recording head is a magnetic recording head by which a magnetic recording medium is locally heated to reduce the coercive force so that the magnetic recording medium can be easily magnetized by a weak magnetic field. Recently, research has been conducted on a heat-assisted magnetic recording head employing a method in which a magnetic recording medium is heated by irradiating a light beam.
FIG. 1 is a schematic diagram illustrating an example of a recording apparatus 1 including a related art heat-assisted magnetic recording head 15. Referring to FIG. 1, the heat-assisted magnetic recording head 15 is formed at one end portion of a slider 10 which can maintain a floating state from a magnetic recording medium 2 and move to a particular track of the magnetic recording medium 2 while the recording apparatus 1 is operated. An air-bearing surface (ABS) 13 is formed at a surface of the slider 10 facing the magnetic recording medium 2. During the operation of the recording apparatus 1, the magnetic recording medium 2 rotates at high speed, and therefore air flows at high speed between the air-bearing surface 13 and the magnetic recording medium 2. While flowing beneath the air-bearing surface 13, the high-speed airflow provides an upward force to the slider 10 such that the slider 10 separates further from the magnetic recording medium 2. The slider 10 maintains a floating state at a height at which the upward force provided by the high-speed airflow and the elastic pressure of a suspension (not shown) elastically supporting the slider 10 can be in an equilibrium state.
The heat-assisted magnetic recording head 15 includes a waveguide 16 and a grating coupler 17 formed on a front surface of the waveguide 16. Light beams Lo emitted by an external light source (not shown) are absorbed into the waveguide 16 by means of the grating coupler 17, are transmitted along the waveguide 16, and are emitted toward the magnetic recording medium 2 (please refer to Ls).
However, the recording apparatus 1 must comprise a complicated collimating means (not shown) for directing the light beams Lo toward the grating coupler 17. In addition, even though the recording apparatus 1 comprises the complicated collimating means, since even a minute shaking of the slider 10 and the relatively large size of light beams prevent some light beams from being absorbed into the waveguide 16, loss of light beams is relatively large. Further, since light beams not absorbed into the waveguide 16 are diffusedly reflected off the grating coupler 17 and travel to the magnetic recording medium 2 and the diffusedly reflected light beams Lr affect magnetization states of the magnetic recording medium 2, noise may be generated.